Abstract 513: Emre Regulates the Mitochondrial Calcium Uniporter in vivo

2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Julia C Liu ◽  
Nicole Syder ◽  
Nima Ghorashi ◽  
Thomas B Willingham ◽  
Randi J Parks ◽  
...  
Keyword(s):  
Ischemia Reperfusion Injury ◽  
Transmembrane Protein ◽  
Ischemia Reperfusion ◽  
Strenuous Exercise ◽  
Mitochondrial Calcium ◽  
Mitochondrial Calcium Uniporter ◽  
Isolated Mitochondria ◽  
Mendelian Genetics ◽  
Calcium Uniporter

Mitochondrial uptake of Ca 2+ plays critical roles in cardiac energy production as well as cell death. The mitochondrial calcium uniporter in mice and humans is a multi-protein complex that includes the channel-forming protein MCU and several other subunit proteins, including EMRE. EMRE is a single transmembrane protein that is conserved among metazoan species and is known to be essential for mitochondrial Ca 2+ uptake in cell culture. To investigate EMRE’s role in organismal physiology, we generated a mouse model of global germline EMRE deletion. We show that EMRE is indeed required for mitochondrial calcium uniporter function in isolated mitochondria from multiple tissues. Although the birth rate of Emre -/- mice is lower than expected by Mendelian genetics (~5-10% instead of ~25%), the mice that are born are viable and appear healthy. Oxygen consumption in isolated mitochondria and cells is not significantly affected by loss of EMRE, and similarly the mice do not exhibit overt metabolic impairment, even under strenuous exercise. No significant differences between Emre -/- and wild-type ( WT ) cardiac function at baseline and after isoproterenol stimulation are evident by echocardiography. Moreover, Emre -/ - hearts are not protected from ischemia/reperfusion injury in a Langendorff perfusion model (mean infarct area 61% in Emre -/- hearts; 57% in WT ). Collectively, these data and their similarities to results found via germline Mcu deletion demonstrate that EMRE is indeed essential for mitochondrial Ca 2+ uptake in vivo. Furthermore, we find evidence that EMRE protein expression is elevated in some mouse muscular dystrophy models, suggesting that modulation of EMRE levels may play a role in regulating uniporter activity in conditions of stress or disease. We therefore further explore whether and how EMRE expression changes with isoproterenol-induced cardiac hypertrophy in mice and in samples from human patients with heart failure. Understanding of how uniporter components such as EMRE can regulate MCU in a diseased state can inform better therapeutic strategies aimed at restoring mitochondrial metabolic homeostasis.

Abstract 435: The Mitochondrial Calcium Uniporter is Necessary for Cardiac Energetic Signaling During Chronic Stress

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Timothy S Luongo ◽  
John W Elrod
Keyword(s):  
Chronic Stress ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Cardiac Contractility ◽  
Permeability Transition Pore ◽  
Permeability Transition ◽  
Mitochondrial Calcium ◽  
Mitochondrial Calcium Uniporter ◽  
Calcium Uniporter ◽  
Stress States

The mitochondrial calcium uniporter (MCU) is a multicomponent channel that is the primary mechanism for mitochondrial Ca 2+ uptake ( m Ca 2+ ). We previously reported that the MCU is required for energetic signaling to meet contractile demand during the ‘fight or flight’ response. In addition, we showed that deletion of the pore-forming component ( Mcu gene) protected against mitochondria permeability transition pore (MPTP) opening and ischemia-reperfusion injury. However, results from our study and others questioned the physiological relevance of MCU-mediated Ca 2+ uptake during chronic stress states featuring sustained intracellular Ca 2+ load ( i Ca 2+ ). To address this, we deleted Mcu from cardiomyocytes in adult mice ( Mcu cKO) and implanted osmotic pumps to deliver the β adrenergic agonist isoproterenol (iso, 70 mg/kg/day for 14d). In contrast to controls, Mcu cKO mice lacked contractile responsiveness to chronic βAR stimulation with evidence of LV dysfunction and failure by d14 ( Fig 1 ). Next, we crossed the Mcu cKO with mice overexpressing the β2a subunit (β2a-Tg) of the L-type Ca 2+ channel (LTCC). This model displays enhanced LTCC activity and cardiac contractility, but with added stress such as iso infusion, Ca 2+ overload eventually leads to MPTP-dependent cell death and heart failure. Surprisingly, loss of Mcu in this model was lethal with all mice dying by d13 ( Fig 2 ). Baseline echocardiography revealed that loss of Mcu ablated all β2a-mediated enhancements in LV contractility and accelerated dysfunction post-iso. These findings demonstrate that MCU-mediated m Ca 2+ uptake is critical to meet energetic demand during chronic stress states featuring sustained i Ca 2+ load.

Orientin Protects Cardiomyocytes against Reperfusion via Mitochondrial Calcium Uniporter

2011 ◽  
Vol 80-81 ◽  
pp. 757-761 ◽  
Author(s):  
Na Lu ◽  
Xiao Xiang Zheng
Keyword(s):  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Research Area ◽  
Mitochondrial Pathway ◽  
Mitochondrial Calcium ◽  
Cytochrome C Release ◽  
Mitochondrial Calcium Uniporter ◽  
Beneficial Effects ◽  
Calcium Uniporter ◽  
Bamboo Leaves

Orientin, isolated from bamboo leaves, is an important natural antioxidant. It has been identified that orientin could protect myocardium against ischemia/reperfusion (I/R) injury, and mitochondrial pathway might be involved in this effect. But the precise mechanism underlying this protective effect is still elusive. Mitochondrial channels are proved to be the important effectors of cell life and death. Especially, mitochondrial calcium uniporter (MCU) has shown particular contribution to cardiomyocytes under specific pathological or physiological conditions. The role of MCU in regulating I/R-induced heart injury is a novel research area. In addition, the relationship of orientin and MCU in mediating reperfusion-induced cardiomyocytes injury is still elusive. In the present study, we used H9c2 cardiomytocytes to investigate the effect of orientin on MCU during reperfusion. Our results indicated that orientin could prevent the MCU opening in H9c2 cells subjected to I/R injury. Further investigation revealed that this effect was correlated with orientin-attenuated reactive oxygen species (ROS) production, depolarization of mitochondrial membrane potential (Δψm), mitochondrial cytochrome c release and mitochondrial Ca2+ accumulation. Our results suggested that these beneficial effects of orientin were partially blocked by spermine, an activator of MCU. In summary, the findings indicate that orientin protects H9c2 cardiomytocytes against ischemia/reperfusion injury via inhibiting mitochondrial calcium uniporter opening，and PI3K/Akt signaling pathway may be involved in these effects of orientin.

scholarly journals A novel protoapigenone analog RY10-4 induces apoptosis of breast cancer cells by regulating mitochondrial Ca2+ influx through the mitochondrial calcium uniporter

2020 ◽  
Author(s):  
Pingping Xue ◽  
Qian Chen ◽  
Xiuhua Ren ◽  
Yimin Yang ◽  
Xiaofan Yang ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Flavonoid Compound ◽  
Mitochondrial Calcium ◽  
Mitochondrial Apoptosis ◽  
Apoptosis Pathway ◽  
Mitochondrial Calcium Uniporter ◽  
Calcium Uniporter

Abstract Background Protoapigenone, as a flavonoid compound with a specific nonaromatic B-ring, exhibits extraordinary antitumor activities against a broad spectrum of human cancer cells. Here we developed a novel protoapigenone analog RY10-4, which induces the apoptosis of various tumor cells, especially for breast cancer cells, but the underlying mechanism involved in the apoptotic process remains unclear. Methods MTT assay, colony-formation assay and flow cytometry were applied to evaluate the proliferation and apoptosis of breast cancer cells. Cytoplasmic calcium ([Ca2+]c) and mitochondrial calcium ([Ca2+]m) of the breast cancer cells were measured by the Fluo-2 and Rhod-2 probes, respectively. The mitochondrial reactive oxygen species (mtROS), membrane potential (ΔΨm) and permeability transition pore (mPTP) were analyzed by MitoSOX, JC-1 probes and Calcein/AM, respectively. Furthermore, Western bolt assay was adopted for the exploration of the mitochondrial apoptosis pathway. Besides, the xenograft assay was performed to investigate the role of RY10-4 in breast cancer cells in vivo. Results Obviously, RY10-4 could effectively suppress the proliferation and induce the apoptosis of breast cancer cells. Furthermore, the [Ca2+]c and [Ca2+]m of MDA-MB-231 cells were up-regulated after the treatment of RY10-4, resulting in the mtROS accumulation, ΔΨm depolarization and mPTP opening. And finally, the mitochondrial apoptosis was activated by the release of cytochrome C. Interestingly, the inhibition of mitochondrial calcium uniporter (MCU) with Ru360 attenuated the overload of [Ca2+]m and blocked the apoptosis of MDA-MB-231 cells induced by RY10-4, which was also consistent with the in vivo results. Conclusions From the results we concluded that RY10-4 could induce apoptosis of breast cancer cells by elevating [Ca2+]m through MCU. Our work contributed previously unknown insights into the mechanisms involving in the clinical efficacy of RY10-4 on breast cancer cells, which also advanced calcium homeostasis as a potential target for chemotherapeutic drugs.

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